1. Field of the Invention
The present invention relates generally to apparatus for removing contaminants from dredge material. More specifically, the present invention relates to a reactor vessel which generates a slurry vortex to treat contaminated sediments in an underwater environment.
2. Description of the Prior Art
At present, technologies for managing contaminated dredge material in an under water environment require elaborate contaminant separation, handling, treatment and disposal facilities and processes. Innovative dredge heads have been designed during the last decade in an attempt to mitigate the environmental impact of dredging in conjunction with site specific operations for the removal of contaminants from the ocean floor and monitoring procedures for determining the level of contamination.
Nevertheless, physical removal of contaminated sediments by conventional dredging technologies invariably results in contaminant losses and off site migration due to the generation of sediment plumes and desorption of contaminants when exposed to oxidizing lacustrine or sea water. Following removal, highly contaminated dredged material can be classified as hazardous waste, requiring physical separation from "clean spoils", or non-contaminated sand and soils, special handling, ex situ treatment and/or expensive disposal in land based hazardous waste sites. The disposal of highly contaminated dredged material can be very costly, i.e., up to one thousand dollars per cubic yard. There is also the additional problem of filling land fills with contaminated sediments since these land fills generally have limited available space for hazardous waste disposal.
In many cases, severe contaminated sediments are derived from a single pollutant source, such as a shore-based industrial facility which has dumped contaminants into a nearby stream or river or directly into the lake or ocean. In these cases the contamination is often concentrated in "hot spots" in close proximity to their source.
Accordingly, there is a need to provide for a reactor vessel device which allows for in situ cleanup of highly contaminated sediment reducing "hot spot" sediment contaminant levels. Reducing "hot spot" sediment contaminant levels allows for the leaving of cleaned sediments in their place, or for the removal and disposal by conventional dredging methods with minimal environmental risk.